diff options
| -rw-r--r-- | Makefile.am | 3 | ||||
| -rw-r--r-- | src/util/util.h | 4 | ||||
| -rw-r--r-- | src/util/util_lock.c | 83 |
3 files changed, 89 insertions, 1 deletions
diff --git a/Makefile.am b/Makefile.am index 07dcbd21..3306bbac 100644 --- a/Makefile.am +++ b/Makefile.am @@ -507,7 +507,8 @@ libsss_util_la_SOURCES = \ src/util/murmurhash3.c \ src/util/atomic_io.c \ src/util/sss_selinux.c \ - src/util/domain_info_utils.c + src/util/domain_info_utils.c \ + src/util/util_lock.c libsss_util_la_LIBADD = \ $(SSSD_LIBS) \ $(UNICODE_LIBS) \ diff --git a/src/util/util.h b/src/util/util.h index de9e6b89..d9315aef 100644 --- a/src/util/util.h +++ b/src/util/util.h @@ -559,6 +559,10 @@ struct sss_domain_info *new_subdomain(TALLOC_CTX *mem_ctx, struct sss_domain_info *copy_subdomain(TALLOC_CTX *mem_ctx, struct sss_domain_info *subdomain); +/* from util_lock.c */ +errno_t sss_br_lock_file(int fd, size_t start, size_t len, + int retries, useconds_t wait); + /* Endianness-compatibility for systems running older versions of glibc */ #ifndef le32toh diff --git a/src/util/util_lock.c b/src/util/util_lock.c new file mode 100644 index 00000000..c2d7fac7 --- /dev/null +++ b/src/util/util_lock.c @@ -0,0 +1,83 @@ +/* + SSSD + + util_lock.c + + Authors: + Michal Zidek <mzidek@redhat.com> + + Copyright (C) 2012 Red Hat + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. +*/ + +#include <unistd.h> +#include <fcntl.h> +#include <errno.h> + +#include "util/util.h" + +errno_t sss_br_lock_file(int fd, size_t start, size_t len, + int retries, useconds_t wait) +{ + int ret; + struct flock lock; + int retries_left; + + lock.l_type = F_WRLCK; + lock.l_whence = SEEK_SET; + lock.l_start = start; + lock.l_len = len; + lock.l_pid = 0; + + for (retries_left = retries; retries_left > 0; retries_left--) { + ret = fcntl(fd, F_SETLK, &lock); + if (ret == -1) { + ret = errno; + if (ret == EACCES || ret == EAGAIN || ret == EINTR) { + DEBUG(SSSDBG_TRACE_FUNC, + ("Failed to lock file. Retries left: %d\n", + retries_left - 1)); + + if ((ret == EACCES || ret == EAGAIN) && (retries_left <= 1)) { + /* File is locked by someone else. Return EACCESS + * if this is the last try. */ + return EACCES; + } + + if (retries_left - 1 > 0) { + ret = usleep(wait); + if (ret == -1) { + DEBUG(SSSDBG_MINOR_FAILURE, + ("usleep() failed -> ignoring\n")); + } + } + } else { + /* Error occurred */ + DEBUG(SSSDBG_CRIT_FAILURE, + ("Unable to lock file.\n")); + return ret; + } + } else if (ret == 0) { + /* File successfuly locked */ + break; + } + } + if (retries_left == 0) { + DEBUG(SSSDBG_CRIT_FAILURE, ("Unable to lock file.\n")); + return ret; + } + + return EOK; +} |